Pretoria is expected to be the hottest of the three cities on Friday, with the temperature climbing to 33°C, according to AccuWeather.
The forecast describes conditions as very warm with sunshine and a few clouds.
Johannesburg will also be warm, reaching a high of 30°C, with mostly cloudy conditions.
Both Johannesburg and Pretoria have a maximum UV index of 11, classified as extreme.
Cape Town much cooler
Cape Town will be considerably cooler, with a high of 20°C on Friday.
The day is forecast to start with clouds before the sky brightens. The forecast shows no expected rainfall.
Winds will reach 17 km/h from the WNW, with gusts of up to 32 km/h.
Overnight temperatures
Cape Town is expected to fall to 13°C, with partly cloudy conditions developing. Winds will be from the SSE at 15 km/h, with gusts reaching 32 km/h.
Johannesburg will drop to 15°C under partly cloudy skies, while Pretoria will remain warmer at 18°C.
In Johannesburg, the chance of rain overnight is 4%, while Pretoria has a 3% chance. Cape Town has just a 1% chance of rain overnight.
Kabous Le Roux
www.ewn.co.za
